, but the specification doesn't allow for minus signs. \d contains only digits 0-9 and nothing else. Maybe you want to widen your spec to
On some test data that I made up, I didn't get any warnings. Maybe you have something that would help, something more specific? As it is, it doesn't seem like you should be getting any warnings, but you may be using an antiquated perl which might not work like the 5.6.1 that I tested on.